Internal combustion-type engines mix controlled quantities of filtered air and fuel. The resultant mixture is fed to an interior of an intake manifold, from which it is distributed to a cylinder for combustion. During compression of the fuel-air mixture by the piston in a particular cylinder, certain quantities of blow-by carbonaceous particles and gases leak into the crankcase past the piston rings of the engine and become trapped therein with contaminants, such as oil vapors emitted by heated engine-lubricating oil.
Modern automobile engines have been equipped with a positive crankcase ventilation (PCV) system which is disposed in an oil and oil vapor recirculation line connecting the crankcase and the intake manifold. This allows the engines to recycle the contaminated oil and oil vapors back into the combustion chamber. In such a system, a stream of fresh air is directed into the engine interior wherein it re-circulates, picking up the vapors therein. The contaminated oil and oil vapors then leave the crankcase through a PCV valve and are conducted by conduit means to the intake manifold, where the dirty oil and oil vapors mix with the fuel-air mixture and are distributed to the cylinders for combustion.
It has been recognized that the oil and other contaminants mixing with the hot vapors in the crankcase and, thereafter, reaching the intake manifold and combustion cylinders, has a number of undesirable effects on engine performance. These undesirable effects can include, but are not limited accumulation of non-combustible residues on engine intake and exhaust valves; increased exhaust emissions and decreased fuel mileage due to incomplete combustion; which can be caused by dilution and contamination of the air and fuel; and the necessity of enriching the fuel-air mixture to off-set the loss of power therefrom.
Due to the advent of the new alternative fuels used in automotive engines, i.e. such as E-85 and compressed natural gas, it is ever more important to prevent the intermixing of the contaminating PCV oil and oil vapors with these lesser BTU fuels.
In addition, additives, such as detergents, are typically added to fuel. Such additives are used to clean deposits off of internal parts of the engine, such as the intake and exhaust valves. Some of these deposits may be a direct result of re-introducing the contaminating oil and oil vapors with a conventional PCV system and/or from other particulates that hinder the combustion process. The use of additives to break down these deposits may result in additional exhaust emissions being fed into the combustion process
What is needed is an improved system for reducing and/or eliminating contaminates, such as oil, carbonaceous material, etc., from the dirty oil and oil vapors to provide cleansed air to be remixed with fuel for combustion. In addition, a more efficient system is needed for maintaining an engine air/fuel stoichiometric ratio by maintaining normal intake manifold pressure during various acceleration and deceleration modes.